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Date and Time of the Query: 2019-06-17 T11:46:54 PDT
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For refcode 2008A&A...485..695C:
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Copyright by European Southern Observatory (ESO). Reproduced by permission
2008A&A...485..695C On the morphology of {sigma}-drop galaxies Comeron, S.; Knapen, J. H.; Beckman, J. E. Abstract. Context: Local reductions of the stellar velocity dispersion in the central regions of galaxies are known as {sigma}-drops ({sigma}-drops). Knowing the origin of these features can lead to better understanding of inner galactic dynamics. Aims: We present a sample of 20 {sigma}-drop galaxies matched with a control sample of galaxies without {sigma}-drop in order to search for correlations between {sigma}-drops and the properties, primarily morphological, of the nuclear zones and discs of their host galaxies. Methods: We study the dust and H{alpha} distribution at 0.1 arcsec scale, using Hubble Space Telescope imaging, in the circumnuclear zones of the two samples of galaxies, searching for differences and trying to establish a link between the nuclear kinematics and the host morphology. We have also considered the CO and H i emission of the galaxies and their luminosity profiles. Results: We classify the two samples following both morphological parameters and the luminosity profiles. We find a larger fraction of nuclear dust spirals and H{alpha} rings in the {sigma}-drop sample. We also find that the fraction of Seyfert galaxies in the {sigma}-drop sample is bigger than that of LINERs and that the reverse is true for the control sample. Conclusions: Our findings are evidence that a {sigma}-drop is very probably due to inflow-induced star formation in a dynamically cool disc, or in a gas ring, shock focused by an inner Lindblad resonance above a certain critical density level. The same mechanism that feeds the nuclear ring or the nuclear disc is probably reponsible for the higher rate of Seyfert galaxies among the {sigma}-drop hosts. Key words: Galaxy: kinematics and dynamics, galaxies: nuclei, galaxies: statistics
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